Construction of MnO2/micro-nano Ni-filled Ni foam for high-performance supercapacitors application

The MnO2/Micro-nano Ni-filled Ni foam (MNFNF) hybrids were systematically studied as supercapacitor electrodes. Micro-nano Ni-filled Ni foam (MNFNF) was prepared via a facile NiC(2)O(4 center dot)2H(2)O coating process on foam, followed by sintering treatment, and then employed as substrate for electrodeposition of MnO2. The morphology of the MNFNF substrate exhibited an obviously second-porous structure, deriving from dehydration, decarboxylation, and the lattice contraction occurred in the sintering treatment process of NiC(2)O(4 center dot)2H(2)O. The structure of pores was irregular with 0.05 similar to 2 mu m in diameter, and the pore walls were composed of nanoparticles with 200 similar to 500 nm in diameter. Such porous MNFNF not only provided a conductive network to enhance the charge transport and mass transfer in the electrochemical process but also achieved a large MnO2 mass loading capacity. Electrochemical test showed the MnO2/MNFNF electrode exhibited a mass specific capacitance (SC) of 723.7 F g(-1) and an areal specific capacitance of 1.16 F cm(-2) at a current rate of 0.25 A g(-1). The asymmetric supercapacitor device based on the MnO2/MNFNF electrode and active carbon electrode could supply an energy density of 24.5 Wh kg(-1) at the maximum power density of 4.4 kW kg(-1). Meanwhile, the supercapacitor device also exhibited a good cycling stability along with 93.2% specific capacitance retained after 5000 cycles. These results demonstrated that the MnO2/MNFNF electrode could be one of the potential electrode material for energy storage applications.